Climate change is often treated like something that won’t be harmful for many decades. The truth is that we’re already feeling the effects of greenhouse gas emissions—and they’ll become more and more prevalent as time goes on. Take ocean acidification—the change in ocean chemistry due to the absorption of CO2 from the atmosphere. The degree of acidification is already beyond the likely range of natural variability of the past thousand years. Acidification has already been linked to impacts on marine life, as a report on a commercial oyster hatchery in Oregon indicated earlier this year.

One of the regions most sensitive to acidification is the Southern Ocean surrounding Antarctica. Lots of deep ocean water rises to the surface here, bringing with it the nutrients that fuel plankton blooms and a feeding frenzy that goes right up the food chain.

That deep water hasn’t seen the surface in a thousand years, and it contains high concentrations of dissolved CO2. In the same way that breathing into a small bag quickly makes the air inside it “stale” (ignoring, for the moment, the garlic you had for lunch), CO2 accumulates in the deep ocean over time. That addition of CO2 makes the water a little more acidic, similar to the way that human emissions are affecting the shallow ocean.

Deeper water also contains less carbonate, which stabilizes pH and provides the raw materials to build shells for many organisms. When CO2 dissolves in water, it reacts with carbonate, making it unable to perform as a buffer against change. All this makes the Southern Ocean less resilient to the effects of acidification than other regions.

That’s bad news for the droves of plankton that help form the base of this critical food web and build their tiny shells from calcium carbonate. When the concentrations of calcium and carbonate in water are greater than the chemical saturation point, calcium carbonate minerals (calcite and aragonite) can readily form. If they are undersaturated instead, calcium carbonate minerals will dissolve—including the shells of marine organisms.

Pteropods (tiny gastropods are sometimes called “sea butterflies” because of the flaps they use to swim) are key plankton in the Southern Ocean, and researchers have been interested in the impact that ocean acidification could have on them. Rather than study their response to future conditions in the lab, a group of scientists working on a research vessel in the Southern Ocean decided to capture live specimens and examine the shape they were in at present.

They collected pteropods from nine locations along a line heading north (naturally) from Antarctica to the island of South Georgia. In eight of those locations, the specimens looked pretty good, as in the left side of the image above. The ninth location, however, was a different story. There, dissolution of the shells was quite apparent (right side of image above)—the handiwork of acidic water with low carbonate concentrations.

For comparison, some of the healthy-looking pteropods were brought on board and placed in tanks with varying amounts of CO2 pumped into the water, which affects the amount of carbonate that’s available. To reach the ragged state of the specimens they had caught, the pteropods had to spend roughly a week near or below the calcium carbonate saturation point.

The water column at the location where the beat-up looking pteropods were caught was chemically different from the others. The depth at which the water dropped to the calcium carbonate saturation point (or lower) was much closer to the surface, where the pteropods live. That’s because upwelling was a little stronger there than at the other sampling spots. The pteropods manipulated onboard showed that four to eight days of those conditions would be enough to damage their shells.

So if the culprit here is upwelling, what does human-caused acidification have to do with it? As deep water rises to the surface, it mixes with the shallow water. The more acidic the shallow water is (due to anthropogenic CO2), the less it’s able to compensate for the deep water. The result? The pteropods experience stronger acidity than they would have without human influence.

Average carbonate saturation and pH in the Southern Ocean has already decreased measurably due to rising atmospheric CO2. On average, aragonite—the calcium carbonate mineral that pteropod shells are composed of—is projected to become undersaturated by about 2050. Between now and then, damage to pteropod shells from upwelling will become increasingly common. That’s an important thing to recognize. Pteropod populations could be significantly impacted long before 2050.

It’s important to note the ragged-looking pteropods the researchers observed aren’t necessarily dying. There are additional variables in play here, but damage to the shell compromises the pteropod’s defenses against predators and infections. We don’t know how much damage it takes before the population takes a hit. It could be that the actual harm isn’t as bad as it looks. Of course, uncertainty cuts both ways— it could be that it’s worse.

95 Reader Comments

I applaud Ars for constantly bringing these issues of the ocean problems to everyone's attention. It is something I feel that people do not fully understand the implication of what could happen if we really screw up the ocean.

While I am glad to see its not everywhere yet it does show we are e facing a larger issue especially with the plankton. The ocean I believe is one of the largest contributors for our oxygen supply right now producing around 50% of our oxygen which of course comes from the plankton.

Glad to see a post like this, how many people think of the consequences of our actions for areas such as the ocean (outside of "sea-level rise")? So many people haven't taken a basic ecology course and the amount of scientific ignorance in our country to climate change is just staggering, hopefully research like this that is easy to see (not requiring complex computer models) will help change that.

Also the "normal" climate of our planet is colder than it is now. Warm periods, like the one we are in, are short lived.

Perhaps you have a working model with data for how ocean acidification "just happens" that you'd like to share with everyone else?

It's a lot simpler even than even global warming: dumping CO2 in the oceans causes their Ph to change dramitically. We are unquestionably dumping CO2 into the oceans. Their Ph is changing dramatically.

Carbon emissions or not, the climate WILL change - and change drastically - in the future. How quixotic to spend trillions fighting such a thing.

This is the latest line of defense. First it was "Well, it's not happening", then it was "Well, it's happening, but not very much". Then it was "Well, it's happening, but humans aren't the cause." Then it became, "Well, it might be man-made and an issue, but not much of one". It seems like we're now hearing "Well, it's an issue, but the climate's always changing anyway and the world has seen worse".

Pretty soon, I expect to see "Well, it's happening, and it's causing problems, but we should just make the best of it".

I don't think anyone's proposing spending trillions to stop climate change that's totally outside our control---that's a strawman---it's to stop climate change that happening at an unprecedented rate and could have potentially significant socioeconomic impacts. We don't quite now how bad it might be, but it could be very bad, and it takes time to deal with that, so why not hedge our bets and try to stop it, or at least make it less bad.

George Carlin's take: The planet is fine, it's humanity that's f_cked" sums it up rather nicely. I don't know about you, but I"d rather my children and grandchildren not be involved in wars over arable land.

It's a normal cycle. The globe warms and cools and causes the ocean's ph to change as well. It's nothing to be alarmed about.

Change happens yes, the problem is not so much the change, but the speed of change, and it is going VERY fast. The faster the change the harder it will be for species to adapt. The big species (vertebrate) because they are more complex, have longer generations, and have less population, have a hard time evolving, and much of them are already facing human-related problems (pollution, less habitat). So they might not be able to evolve fast enough.

It's a normal cycle. The globe warms and cools and causes the ocean's ph to change as well. It's nothing to be alarmed about.

Change happens yes, the problem is not so much the change, but the speed of change, and it is going VERY fast. The faster the change the harder it will be for species to adapt. The big species (vertebrate) because they are more complex, have longer generations, and have less population, have a hard time evolving, and much of them are already facing human-related problems (pollution, less habitat). So they might not be able to evolve fast enough.

What's even more sensitive here than species is economics. We (as a species) have been through much worse, the planet anyway, but fast changes are easily catastrophic economically, and politically. All this "life will adapt" is both totally true and incredibly idiotic. Life as such will adapt and survive in the long run, but many individuals, states, economies and societies will not.

I don't know about you, but I"d rather my children and grandchildren not be involved in wars over arable land.

So you would rather they went to war over their entitlement? You attached a condition to the inevitable.

In any event, I'm wondering how well they can truly separate natural tectonic plate pollution from the anthropogenic contribution. Did Eyjafjallajökull have any effect? How comparable was the eruption to collective human activity over one year?

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By looking at isotopes. Carbon Dioxide emitted by humans is from plants which has a different isotope mix.

It's a normal cycle. The globe warms and cools and causes the ocean's ph to change as well. It's nothing to be alarmed about.

Warming and cooling by itself doesn't change the pH of the ocean as much as increasing the CO2 in the atmosphere above it. Doing that is the biggest switch on oceanic pH. These changes are happening as a direct effect of CO2 emissions, not a side effect of warming. The problem is exacerbated if the rate of atmospheric CO2 increase is greater than the rate at which the ocean can sequester dissolved CO2 in deep waters and the buffering calcium carbonates. Current rates of atmospheric CO2 increase are about 100 times greater than in the past, which doesn't give the ocean enough time to lock the CO2 away so it piles up and lowers the pH of the seas as a whole. In fact we're dumping CO2 into the atmosphere many times faster than during ecological disasters like the Permian extinction. Not by coincidence, the ocean's pH is also changing faster than at any point in the geological record other than even the most extreme events. And no, oceanic pH level are not cyclical, because CO2 levels and rates of increase in the past were not cyclical. Our current rate of acidification is shaping up to be the fastest its been in the past 300 million years at least. Remember that it's the rate of atmospheric CO2 increase that largely determines the severity of ocean acidification. But don't take my word for it. Consult NOAA or the Woods Hole Oceanographic Institute and see what they have to say about ocean acidification.

Also, you still owe me some sources to support your contention in the other thread about speciation not being observed despite the evidence I provided to the contrary.

I'm wondering how well they can truly separate natural tectonic plate pollution from the anthropogenic contribution. Did Eyjafjallajökull have any effect? How comparable was the eruption to collective human activity over one year?

By looking at isotopes. Carbon Dioxide emitted by humans is from plants which has a different isotope mix.

Mmk. So, that's half of the question. Now, when you measure pH, how much can you attribute to either source of pollution? Is the quantity of the isotopes subtracted from the other and its remainder attributed solely to mankind, or are they lumped together in our pH measurement when we go to blame all humans?

I applaud Ars for constantly bringing these issues of the ocean problems to everyone's attention. It is something I feel that people do not fully understand the implication of what could happen if we really screw up the ocean.

While I am glad to see its not everywhere yet it does show we are e facing a larger issue especially with the plankton. The ocean I believe is one of the largest contributors for our oxygen supply right now producing around 50% of our oxygen which of course comes from the plankton.

It's a normal cycle. The globe warms and cools and causes the ocean's ph to change as well. It's nothing to be alarmed about.

This doesn't have to do with temperature change so I don't know why you keep bringing up your irrelevant (and inaccurate) arguments regarding temperature. This has to do with increased levels of CO2 in our oceans which will work their way up the food chain. Harming the food chain so quickly without adequate time to adapt may lead to global starvation.

This doesn't have to do with temperature change so I don't know why you keep bringing up your irrelevant (and inaccurate) arguments regarding temperature. This has to do with increased levels of CO2 in our oceans which will work their way up the food chain. Harming the food chain so quickly without adequate time to adapt may lead to global starvation.

Well, they're linked in so far as CO2 is also a greenhouse gas. But you're right, temperature change alone wouldn't so dramatically change the ph of the oceans and account for the massive increase in rate of change we're seeing.

I'm wondering how well they can truly separate natural tectonic plate pollution from the anthropogenic contribution. Did Eyjafjallajökull have any effect? How comparable was the eruption to collective human activity over one year?

By looking at isotopes. Carbon Dioxide emitted by humans is from plants which has a different isotope mix.

Mmk. So, that's half of the question. Now, when you measure pH, how much can you attribute to either source of pollution? Is the quantity of the isotopes subtracted from the other and its remainder attributed solely to mankind, or are they lumped together in our pH measurement when we go to blame all humans?

It is like this. Say you there are two little boys. Every week one little boy walks past a bush and breaks part of it off. The bush can grow that back. Next another little boy comes by once a week and breaks a bit off the bush. The bush can no longer cope and gets smaller.

If we are the second boy and we can't stop the first boy then the logical thing to do is to alter our own behaviour.

Naturally emitted Carbon Dioxide does increase ocean acidification but there are systems in place that stop it from increasing, it stays level. As humans contribute more and more Carbon Dioxide to the atmosphere then the systems that keep the levels in check can no longer cope.

It is not a matter of asking wether human emitted Carbon Dioxide has more effect on ocean Ph than Natural emissions. It is the sum total of Carbon Dioxide that is the issue. We know that humans are emitting more than natural processes by the isotopes and thus the system that keeps ocean Ph in check will begin to be overwhelmed and the oceans will become more acidic.

Remove human emissions from the planet and we wouldn't see this happen in such a short time frame.

I'm wondering how well they can truly separate natural tectonic plate pollution from the anthropogenic contribution. Did Eyjafjallajökull have any effect? How comparable was the eruption to collective human activity over one year?

By looking at isotopes. Carbon Dioxide emitted by humans is from plants which has a different isotope mix.

Mmk. So, that's half of the question. Now, when you measure pH, how much can you attribute to either source of pollution? Is the quantity of the isotopes subtracted from the other and its remainder attributed solely to mankind, or are they lumped together in our pH measurement when we go to blame all humans?

It is like this. Say you there are two little boys. Every week one little boy walks past a bush and breaks part of it off. The bush can grow that back. Next another little boy comes by once a week and breaks a bit off the bush. The bush can no longer cope and gets smaller.

If we are the second boy and we can't stop the first boy then the logical thing to do is to alter our own behaviour.

Naturally emitted Carbon Dioxide does increase ocean acidification but there are systems in place that stop it from increasing, it stays level. As humans contribute more and more Carbon Dioxide to the atmosphere then the systems that keep the levels in check can no longer cope.

It is not a matter of asking wether human emitted Carbon Dioxide has more effect on ocean Ph than Natural emissions. It is the sum total of Carbon Dioxide that is the issue. We know that humans are emitting more than natural processes by the isotopes and thus the system that keeps ocean Ph in check will begin to be overwhelmed and the oceans will become more acidic.

Remove human emissions from the planet and we wouldn't see this happen in such a short time frame.

There's a problem with this analysis, there is no control. It's possible that the plankton have had imperfect shells in this region for a long time, just as a result of the higher rate of upwelling of deep carbonate depleted water. The explanation that the surface waters ph is the culprit isn't proven by the presented data, making the article merely about a hypothesis and some tangential data. A true control would be to have samples of these shells from this location for many many years, along with upwelling data and chemistry that is consistent in this location for the same number of years, or if inconsistent, a means to correlate. This would them provide an objective test of the hypothesis.

I'm all for finding proof that encourages us to be proactive about the environment, but a critical look at this story reveals this isn't it.

There's a problem with this analysis, there is no control. It's possible that the plankton have had imperfect shells in this region for a long time, just as a result of the higher rate of upwelling of deep carbonate depleted water. The explanation that the surface waters ph is the culprit isn't proven by the presented data, making the article merely about a hypothesis and some tangential data.

I'm all for finding proof that encourages us to be proactive about the environment, but a critical look at this story reveals this isn't it.

I think you're reading the article and assuming "facts" without reading and comprehending the paper and research behind the article.

There's a problem with this analysis, there is no control. It's possible that the plankton have had imperfect shells in this region for a long time, just as a result of the higher rate of upwelling of deep carbonate depleted water. The explanation that the surface waters ph is the culprit isn't proven by the presented data, making the article merely about a hypothesis and some tangential data.

I'm all for finding proof that encourages us to be proactive about the environment, but a critical look at this story reveals this isn't it.

I think you're reading the article and assuming "facts" without reading and comprehending the paper and research behind the article.

If there are controls presented in the paper that were not in the article, then IMO they should be added to solidify the case

I'm going to laugh when I see the looks on faces of people like you when we get irreversible plankton die-offs and uncontrollable algae blooms.

Enjoy the price of fresh tuna while it's still below $10,000/kg.

I won't. If viable fishing grounds essentially disappear, more than the price of what fish can be caught will change. Expect countries that rely on fishing as a primary source of protein to run into severe economic issues as they try to replace fisheries with imported proteins and farmed fish (which comes at its own cost in terms of pollution). Expect prices on all agricultural goods to rise substantially given the overall shortage that would be cause by a loss of viable fisheries. And lets not get into what happens if the oceans ability to clean and output oxygen is diminished in a tangible manner, since the worlds oceans are responsible for about 50% of our breathable air. There's plenty of awful to go around.

There's a problem with this analysis, there is no control. It's possible that the plankton have had imperfect shells in this region for a long time, just as a result of the higher rate of upwelling of deep carbonate depleted water. The explanation that the surface waters ph is the culprit isn't proven by the presented data, making the article merely about a hypothesis and some tangential data. A true control would be to have samples of these shells from this location for many many years, along with upwelling data and chemistry that is consistent in this location for the same number of years, or if inconsistent, a means to correlate. This would them provide an objective test of the hypothesis.

I'm all for finding proof that encourages us to be proactive about the environment, but a critical look at this story reveals this isn't it.

Even though the paper is paywalled, you can still see thumbnails of the figures. Su9 is where these were collected. You'll note that Su8, which is right next door, didn't show this level of dissolution. And they measured the aragonite saturation profile at each location- there's no mystery as to why the dissolution occurred.I don't think the thing you're asking for (samples from that exact spot 10 years ago) is meaningful. Upwelling patterns are chaotic. There's nothing special about that spot, in the long-run.